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http://dx.doi.org/10.4313/JKEM.2015.28.5.326

Shape and Dielectric Strength of Thermal Bubbles in Liquid Nitrogen  

Baek, Seung-Myeong (Department of Fire Safety Engineering, Changwon Moonsung University)
Kim, Hae-Jong (Korea Electrotechnology Research Institute, HVDC Research Division)
Publication Information
Journal of the Korean Institute of Electrical and Electronic Material Engineers / v.28, no.5, 2015 , pp. 326-331 More about this Journal
Abstract
In this paper, we study the insulating properties of the liquid nitrogen(LN2) including the thermal bubbles. The shape of the thermal bubbles in accordance with the current change was observed in the 77 K and 65 K LN2. According to the temperature of liquid nitrogen, bubbles were generated differently. The round shape of the bubble is occurred in 77 K LN2. But the layer shape of bubble is occurred in 65 K LN2. When the bubbles present, the dielectric strength of liquid nitrogen is low. However, the breakdown patterns were different according to the electrode arrangement. AC breakdown voltage(BDV) was lower than the DC BDV due to the influence of bubbles. Therefore, the design of a high-voltage superconducting equipments should consider the bubbles.
Keywords
Thermal bubbles; Temperature; Liquid nitrogen; LN2; AC breakdown voltage; DC BDV;
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Times Cited By KSCI : 1  (Citation Analysis)
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